This investigation is aimed at evaluating the effect of heart disease and hypertension as potentially treatable precursors of stroke and transient ischemic attacks. The objectives of the study are to determine the following: (1) the risk of stroke and transient ischemic attacks in individuals with heart disease and/or hypertension as compared to the risk in individuals without these conditions; (2) whether the existence of pre-existing heart disease and/or hypertension affects the type of stroke and whether it affects survival following stroke; and (3) whether there is a particular time interval following the onset of heart disease or hypertension during which an individual is at high risk for stroke. Data collection for this study has been ongoing since 1973, and it is estimated that an additional year will be required to complete the investigation.